The present invention relates to conveyor belt pulleys, and more particularly to self cleaning wing pulleys that are suited for bulk material handling applications. In these applications, material can stick to or become entrapped behind the conveyor belt. When material is behind the conveyor belt, it is considered debris that must be displaced from the system for optimum conveyor belt traction and belt life.
The use of conventional wing pulleys in belt conveyor applications is a well-known practice which is used for a wide variety of bulk materials. The conventional wing pulley can range from 3.5″ in diameter up to 60″ (and larger) in diameter, and from 4″ in length to 100″ (and longer) in length. Each pulley is constructed from material and thicknesses that are appropriate for the size and rigor of the final application.
The conventional wing pulley design utilizes full length straight wings mated to set of hubs that define the central rotating axis for the pulley. The design and manufacture of the conventional wing pulley is guided by ANSI/CEMA (American National Standards Institute/Conveyor Equipment Manufacturing Association) 501.1-2003(R2009) Specifications for Welded Steel Wing Pulleys.
The conventional wing pulley, while generally considered an ideal self cleaning pulley, has been found to have limitations. When used in bulk material handling applications, the conventional wing pulley does in fact break material loose from the back side of the belt through the impact of the wing on the belt, but the material falls between the wings of the pulley and is re-circulated between the belt and pulley multiple times before being cleared from the system.
The straight wing by design generates a high level of noise. As the straight wings of the conventional pulley come in contact with the moving conveyor belt the impact of the full length wing hitting the belt at single impact creates a slapping sound. Additionally, in conveyor systems handling large belts and material loads, the straight wing pulley has been known to fail due to the straight wing design. As loads are increased, the wings have a tendency to fold over; this is due in part to limited strength of the wings when perpendicularly aligned to the direction belt travel.
Although there is an existing and enduring demand for straight wing pulleys, there remains a need for a formed wing pulley that provide more aggressive belt and debris cleaning capability while providing quieter operation in bulk material handling applications.